HCS301 datasheet(8/38 Pages) MICROCHIP

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HCS301

DS21143C-page 8

of unique values. This can be done by programming

OVR0 and OVR1 to 1s at the time of production. The

encoder will automatically clear OVR0 the first time that

the synchronization value wraps from 0xFFFF to

0x0000 and clear OVR1 the second time the counter

wraps. Once cleared, OVR0 and OVR1 cannot be set

again, thereby creating a permanent record of the

counter overflow. This prevents fast cycling of 64K

counter. If the decoder system is programmed to track

the overflow bits, then the effective number of unique

synchronization values can be extended to 196,608.

3.6.3

BAUD RATE SELECT BITS

(BSL0, BSL1)

BSL0 and BSL1 select the speed of transmission and

the code word blanking. Table 3-3 shows how the bits

are used to select the different baud rates and

Section 5.7 provides detailed explanation in code word

blanking.

TABLE 3-3:

BAUD RATE SELECT

3.6.4

LOW VOLTAGE TRIP POINT

SELECT

The low voltage trip point select bit is used to tell the

HCS301 what VDD level is being used. This information

will be used by the device to determine when to send the

voltage low signal to the receiver. When this bit is set to

a one, the VDD level is assumed to be operating from a

9V or 12V VDD level. If the bit is set low, then the VDD level

is assumed to be 6.0 volts. Refer to Figure 3-1 for volt-

age trip point.

FIGURE 3-1:

VOLTAGE TRIP POINTS

BY CHARACTERIZATION

BSL1

BSL0

Basic Pulse

Element

Code Words

Transmitted

400

μsAll

200

μs

1 out of 2

100

μs

1 out of 2

100

μs

1 out of 4

-40

20 40

100

8.5

7.5

8.0

7.0

9.0

2.5

3.0

3.5

4.0

VLOW

Temp (C)

Volts (V)

VLOW sel = 1

VLOW sel = 0

4.5

-20

60 80

5.0

5.5

Max

Min

Max

Min

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